To extract an interface from a UML class using the GMF-based UML2Tools class-diagram editor, one has to manually go through the following steps:

create and name the new interface

move the methods from the concrete class to the interface

create a generalization between the class and the interface

update all association ends that pointed to the class to now point to the interface

Having a wizard that could do all the above with a single click instead would arguably be a good thing. Even more, having a tool that would allow us to easily define custom wizards at a high level of abstraction by hiding the complexity of GMF would be even better.

Motivated by such scenarios, in the Epsilon GMT component we have implemented a small dedicated language (EWL) and supporting tools that enable users to specify and execute such wizards from within GMF-based editors. Our solution works with existing editors, such as the UML editors provided by the UML2Tools project, without needing to customize or re-generate them. Wizards appear in a sub-menu of the right-click menu and their effects can be undone/redone using the standard Ctrl-Z/Ctrl-Y shortcuts. Wizards are also interactive in the sense that they can prompt the user to provide additional information through standard Eclipse dialogs.

This screencast demonstrates defining and executing a wizard that implements the scenario above, as well as undoing/redoing its effects on the model. A detailed discussion on EWL can be found here and an overview of the GMF/EWL integration can be found here.